Microgyroscope for Determining Rotational Movements About Three Spatial Axes which are Perpendicular to One Another

ABSTRACT

A micro gyroscope for determining rotational movements about three spatial axes x, y and z, which are perpendicular to one another has a substrate (I) on which a plurality of masses ( 2, 3 ) oscillating tangentially about the z axis, which is perpendicular to the substrate (I), are arranged. The oscillating masses ( 2, 3 ) are fastened on the substrate (I) by means of springs ( 5, 6, 8 ) and tie bolts ( 7, 9 ). Driving elements (II) serve to maintain oscillating, tangential vibrations of the masses ( 2, 3 ) about the z axis, as a result of which, upon rotation of the substrate (I) about any spatial axis, the masses ( 2, 3 ) are subjected to Corolis forces and deflections caused as a result. Sensor elements detect the deflections of the masses ( 2, 3 ) on the basis of the Corolis forces generated. Some of the masses ( 2, 3 ) oscillating about the z axis are mounted in a tiltable manner substantially about the x axis which runs parallel to the substrate (I). Others of the masses ( 2, 3 ) oscillating about the z axis are mountable in a tiltable manner substantially about the y axis, which likewise runs parallel to the substrate (I). At least one other of the oscillating masses ( 2, 3 ) can be additionally at least partially deflected substantially radially to the z axis in the x-y plane parallel to the plane of the substrate (I). Said additionally radially deflectable z mass ( 3 ) is assigned a sensor element ( 12 ) which can likewise be deflected radially with respect to the z axis but does not oscillate about the z axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending application Ser. No.13/258,177, filed Sep. 21, 2011, which is the U.S. 371 National Phase ofInternational Application PCT/EP2010/052880, filed Mar. 8, 2010, whichclaims priority to German Application No. 102009001922.7, filed Mar. 26,2009, which applications are hereby incorporated herein by reference intheir entireties and from which applications priority is hereby claimed.

This invention refers to a micro gyroscope for determining rotationalmovements about three perpendicularly stacked spatial axes x, y and zwith a substrate on which several tangentially oscillating masses arearranged about the z axis perpendicularly standing on the substrate,whereby the oscillating masses are fastened to the substrate withsprings and tie bolts and have drive elements for maintaining theoscillating tangential vibrations of the masses about the z axis, as aresult of which the masses are subject to Coriolis forces and thedeflections caused by them when the substrate rotates around any spatialaxis, and with sensor elements for determining the deflection of themasses owing to the generated Coriolis forces.

In an x-y-z coordinate system, micro gyroscopes are generally used fordetermining a rotational movement about an axis. In order to determinethe system's rotations about every one of the three axes, three suchmicro gyroscopes are therefore needed. This is not only very expensive,but it it's difficult to control them and process the data.

A triaxial micro electro-mechanical sensor (MEMS) gyroscope is knownfrom TW 286201 BB in which masses are arranged on a central tie bolt andset into an oscillating rotational motion. These masses are arranged ona substrate and tilted about the x or y axis owing to a Coriolis forcegenerated about the y or x axis, something made possible by acorresponding suspension of these drive masses to the substrate. Whenthere is a rotation about the z axis, partial masses can in turn betranslationally deflected by their corresponding suspension on thepivoted masses. Both the tilting movements and the translator movementcan be determined with sensors, and owing to their proportionality tothe substrate's rotation, it can be used as measure for the respectiverotation about the x, y or z axis. The corresponding deflections,however, can be determined only with great difficulty.

So a tridimensional gyroscope can be created, in which rotations aboutall three axes can be determined, D. Wood and collaborators suggested inan article published in 1996 (“A Monolithic Silicon Gyroscope Capable ofSensing about Three Axes Simultaneously”) a gyroscope with oscillatingmasses arranged circularly about a central tie bolt. These masses arecapable of executing both tilting and rotational movements owing to thegenerated Coriolis forces. The disadvantage, however, is that themanufacturing of such a sensor and the actuation of the moved masses aredifficult. The movements of the individual sensor components influenceeach other, so that measurements of the gyroscope movement in x, y or zdirection are insufficiently accurate.

The task of this invention is to create a highly accurate microgyroscope for determining rotational movements about threeperpendicularly stacked spatial axes x, y and z for determining thedeflections in the individual rotational directions and providing nofalse readings owing to movements in the directions to be determined andthe others, especially not through the actuation of the masses.

The task is solved with a micro gyroscope having the characteristics ofclaim 1.

The micro gyroscope according to the invention serves for determiningrotations about three stacked perpendicular spatial axes x, y and z. Ithas a substrate on which several tangentially oscillating masses arearranged about the z axis placed perpendicularly on the substrate,whereby the oscillating masses are fastened to the substrate by means ofsprings and tie bolts. The drive elements move the masses about the zaxis and maintain an oscillating tangential vibration of the massesabout the z axis. When the substrate is rotating about any spatial axis,Coriolis forces are generated that cause a deflection of the drivenmasses. Sensor elements are arranged in the area of the masses toregister their deflections caused by the Coriolis forces that weregenerated by the substrate's rotational movement.

According to the invention, some of the masses oscillating about the zaxis are arranged essentially in tilted fashion about the x axis runningparallel to the substrate. Other masses oscillating about the z axis arealso arranged in tilted fashion about they axis running parallel to thesubstrate. In addition, at least another one of the oscillating massescan be deflected radially with respect to the z axis, and in the x-yplane parallel to the plane of the substrate. Hereinafter, such masseswill be named “z masses”. An oscillating sensor element that can also bedeflected radially with respect to the z axis, but not about the z axis,is arranged on this z mass that can be additionally deflected radially.

Especially owing to the separation of the z axis from the sensorelement, a decoupling of the tangential drive movement from the radialsensor movement can be accomplished very favorably. The sensor elementitself is not tangentially actuated; therefore, only the radial movementof the sensor element can be registered to determine a rotation of thesubstrate about the z axis. The z mass is moved about the z axistogether with the other masses and deflected in radial direction when arotation of the substrate about the z axis occurs due to the resultingCoriolis force generated by this. The z mass then completes both atangential and radial movement, but only the radial movement istransferred to the sensor element. This sole movement direction of thesensor element in radial direction can be very easily registered withoutsuperimposition with other movements. As a result of this, the recordingaccuracy has been greatly improved compared to the state-of-the-artsolutions.

In accordance with an advantageous design of the invention, thegyroscope consists essentially of eight masses oscillating tangentiallyabout the z axis, in which case four of these masses can be additionallymoved radially about the z axis and are therefore called z masses. Thearrangement of eight oscillating masses from which four are z massescreates a balanced gyroscope with respect to the occurring forces. TheCoriolis forces can be registered relatively easy and the respectivecause of a rotation about a certain axis can be reliably determined. Aparticularly balanced system is achieved especially when the eightmasses are distributed uniformly along the perimeter and the oscillatingmasses are oriented essentially only tangentially about the z axis alongthe x and y directions and the remaining z masses are arranged betweenthe x and y axes. As all masses participating in the drive movement, thez masses are also driven tangentially about the z axis, but can also bedeflected radially to the z axis. These masses are preferably held bysemi-open frames and set into the tangential drive movement. TheCoriolis force merely affects the z mass mobility in radialdirection—thus causing, in turn, the deflection of the sensor elementfor determining a rotational speed about the z axis.

In a favorable design of the invention, the masses that oscillatelargely tangentially about the z axis are tilting plates for registeringthe substrate's rotation about the x or axis. As soon as a Coriolisforce occurs due to the substrate's rotation about the x or y axis,these masses that oscillate only tangentially about the z axis aretilted about the y or x axis. This tilting movement can be converted toelectrical signals with capacitive sensors allocated to the masses.

Advantageously, the both radially and tangentially movable z mass aboutthe z axis can be coupled to a frame so it can be set in tangentialmotion about the z axis. On the one hand, the frame ensures thetangential drive of the z mass and, on the other hand, a stablesuspension of the mass so a movement in radial direction can take place.Owing to the special frame design, the z mass can be made sufficientlylarge so it can show a noticeable reaction to the Coriolis forces and bedeflected in radial direction. This design variant shows clearly thatthe main feature of the z mass is essentially the deflection in radialdirection, which on the one hand can occur only when the entire frameand z mass combination is driven tangentially as primary movement.However, the secondary movement in radial direction is especiallyimportant here. The frame-like design makes it possible to implementthese features very advantageously.

It is especially favorable for the z mass that moves both radially andtangentially about the z axis to be connected to at least another sensorelement for registering its radial deflection caused by the Coriolisforces. As a result of this, the deflections do not have to be measuredat the z mass itself (which moves both in radial and tangentialdirection) but the occurring Coriolis forces that cause the z mass to beradially deflected can be registered by the sensor element that movesonly in radial direction. This leads to a clear improvement of themeasuring results to be registered because there are no superimpositionswith other movements. A movement of the sensor element indicatesexclusively a Coriolis force in radial direction. The signal registeredin this way can therefore be very easily evaluated.

In an advantageous embodiment of the invention, the frame is anchored tothe substrate with springs, especially two, that can be tangentiallymoved about the z axis. Since the frame is essentially stationary in alldirections except the tangential one, it is only capable of oscillatingin tangential direction. The Coriolis forces acting on the frame cannotdeflect it radially. Accordingly, the frame or the springs are thusbuilt stiffly in radial direction. Preferably, the frame does not moveout of the x or y plane either, and therefore does not react to theCoriolis forces that occur as a result of the rotational speeds aboutthe x or y axis. The stiffness in this direction, however, is not alwaysrequired; it can be tolerated for the frame and the z mass to move outof the x-y plane when it is ensured that this movement will not betransferred to the sensor element and affect its measurement.

To obtain a micro gyroscope with a well-balanced system with regard tothe reaction forces and reaction torques occurring between the massesbeing moved, it is better to arrange the frames between the massesoscillating tangentially about the z axis or tilting plates.

The z masses, which can be moved both radially and tangentially aboutthe z axis, are connected to their respective frame with at least onespring, preferably with four springs. This creates a stable arrangementof the z axis within the frame to advantageously ensure that the z masscan be moved only radially relative to the frame. Here, the z massreacts merely to the rotational speeds about the z axis, eliciting aclear reaction of the sensor element allocated to the z mass and acorrespondingly unambiguous measurement result owing to the resultingelectric signal.

If in an advantageous design of the invention the frames are anchored tothe substrate and can be moved mostly tangentially about the z axis,then the primary movement in the frames can be clearly initiated as arotation in tangential direction about the z axis in the frame. Anoscillation in radial direction of the z mass movably arranged withinthe frame is the resulting secondary movement.

The dynamic behavior of the micro gyroscope is significantly enhancedwhen the tilting plates and the frames are connected to one another withsprings. These springs act as synchronization springs and cause theprimary movement (which takes place tangentially about the z axis) to beexecuted by the tilting plates and the frame in the same fashion. As aresult of this, a common mode of oscillation of the tilting plates andthe frame takes place, in which case all masses involved oscillate withequal frequency and phase.

Preferably, the springs (which connect the tilting plates and the frameswith each other) are executed stiffly in tangential direction, butnon-rigidly in the other directions. Therefore, it is possible for theprimary movement occurring in the tilting plates and frames to establisha common mode of oscillation with equal frequency, but the resultingplate tilting out of the x-y plane during an indication of a rotationalspeed in x or y direction is not impeded by the synchronization springs.Thus, the tilting plates can be largely moved independently out of theframe, remaining preferably on the x-y plane without having a largespring resistance that could counteract this.

For the clear indication of a rotational speed about the x or y axis, ithas been advantageously intended for some of the masses or tiltingplates oscillating tangentially about the z axis and other masses ortilting plates to be tiltably anchored to the substrate only about the yaxis. The masses or tilting plates, which are farther away from the xaxis or lie on the y axis and move out of the x-y plane, thereforeindicate a rotational speed about the y axis. On the other hand, themasses or tilting plates farther away from the y axis or lying on the xaxis indicate, while they tilt about the y axis or when they move out ofthe x-y axis, a rotational speed of the sensor about the x axis.

Drive elements that initiate the primary oscillation are preferablyarranged on the masses that oscillate only tangentially about the z axisand/or on the frame. These drive elements initiate a drive oscillationin the structural parts that is a primary oscillation about the z axis.

In an advantageous design of the invention, the drive elements neededfor maintaining the drive oscillation about the z axis are electrodes ofcomb capacitors equipped with the suitable switching drive voltages.Parts of the drive elements are fastened to the substrate foraccomplishing this, other parts are in turn fastened to the structuralelements to be driven. When AC voltage is applied, the electrodes aremutually attracted and this generates the oscillating primaryoscillation of the structural parts.

Sensor elements are preferably arranged below the tilting plates forregistering the deflection of the tilting plates. These sensor elementscan be plate capacitors, for example, whose one movable half is executedon the substrate surface by a tilting plate and whose other, statichalf, by an extended conductor line below the tilting plate. The changeof the capacity during the registration of a measured movement bringsabout a corresponding change of an electrical measured signal.

If sensor elements are allocated to the z masses for registering theradial deflections caused by the Coriolis forces, then the rotationalspeeds about the sensor's z axis above these sensor elements can be veryeasily and unmistakably determined.

Preferably, the sensor elements allocated to the z masses consist ofmovable measuring electrodes of capacitors whose static counterparts arerigidly connected to the substrate. One part of the measuring electrodestherefore also completes the movement of the sensor elements and, whendoing this, either approaches or moves away from the static counterpartsof the measuring electrodes. This spacing change is converted to achangeable electrical signal, which allows one to draw conclusions aboutthe sensor's rotational speed about the z axis.

The movable measuring electrodes of the sensor elements are preferablyexecuted as frames movable in radial direction. This creates a stablestructural element that can reliably signal the movement.

It is especially advantageous for the z masses to be as far away fromthe sensor's center as possible because a stronger Coriolis force canact on them and consequently they can deliver a larger oscillationamplitude to the allocated sensor element. As a result of this, smallrotational speeds can already be measured. In addition, the sensor cannonetheless be built very compactly and with a small surface and deliverclear signals for the corresponding rotational speeds.

To ensure that the sensor element is decoupled as far as possible fromthe tangential movement of the z mass allocated to it, it has beenadvantageously intended for the z mass and the sensor element to beconnected with springs, a non-rigid one in tangential direction and astiff one in radial direction. The radial movement of the z mass is thustransferred to the sensor element and both radial oscillations jointlyproduce the secondary oscillation without the tangential primarymovement of the z mass being capable of interconnecting on the sensorelement.

So the sensor element allocated to the z mass can be stably arranged,especially to make it resistant to influences acting on directions otherthan the intended one as well, it is proposed to fasten the sensorelement to the substrate by means of (preferably) four springs. In thiscase, the springs are executed in a way to allow a radial movement ofthe sensor element but impede movements in other directions as much aspossible.

Preferably, the tilting plate is arranged on the substrate with springsthat allow a tangential-rotational movement of the tilting plate in thex-y plane and a tilting movement of the tilting plate out of the x-yplane. For this purpose, the springs are preferably fixed close to thecenter with a tie bolt.

A preferred design of the sensor's basic form is an essentially circularone for its exterior for supporting the rotation of the primary movementand so the sensor can also fit in a very small structural space.

Other advantages of the invention are described with the help of theembodiments shown in the following figures, which show the figures aslater described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a gyroscope according to the invention,

FIG. 2 is a top view of the tilting plates of the gyroscope according toFIG. 1,

FIG. 3 is the connection of the tilting plates according to FIG. 2,

FIG. 4 is a top view of the z sensor device of the gyroscope shown inFIG. 1,

FIG. 5 is a top view of a z sensor device of the gyroscope according toFIG. 1,

FIG. 6 is a sketch of the primary movement of the sensor according toFIG. 1,

FIG. 7 is a secondary movement for determining a y rotational speed ofthe gyroscope according to FIG. 1, and

FIG. 8 is the determination of a z rotational speed of the gyroscopeaccording to FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The top view of FIG. 1 shows the overview of all components of a microelectromechanical gyroscope in accordance with this invention. Thefigures explain in more detail the individual components as well as thetypes of oscillation of the gyroscope while rotational speeds are beingregistered.

The gyroscope consists especially of elements for registering arotational speed about the x axis and the y axis, which lie on thedrawing plane. Further structural groups of the gyroscope lying on thisplane refer to the detection of the z rotational speed. Parallel to andbelow this plane, there is a substrate on which the structural partsshown are arranged, as described below.

Tilting plates 2 are intended for registering the x and y rotationalspeeds. For determining a z rotational speed (i.e. a rotation of thegyroscope about the z axis) a z mass 3 is essentially placed between twotilting plates 2. The z mass 3 is located in a frame 4 and fastened toit with four springs 5. The frame 4 hangs over two frame springs 6 ontwo frame tie bolts 7 that are fixed to the substrate.

The tilting plates 2 are on the one hand fastened to the substrate withtilting springs 8 and a tie bolt 9. On the other hand, each tiltingplate 2 is held between two frames 4 with two synchronization springs10.

The tilting plates 2 and the z masses 3 with the frame 4 are set into anoscillating rotational tangential motion about the z axis as anoscillating primary movement. In this example, the drive takes placewith the help of two comb electrodes 11 and 11′. Here, the combelectrodes 11 and 11′ are fastened to the movable parts, namely thetilting plates 2 and the frame 4, while the corresponding counterelectrodes 11′ are stationary fixed on the substrate. The application ofalternating voltage elicits the mutual attraction of the electrodes 11and 11′ that are on the opposite sides and this causes the tangentialoscillation of the tilting plates 2 as well as of the z masses 3 andframe 4 in terms of the primary movement. In order to maintain theoscillating rotation of the individual elements in synchrony and thetilting plates 2 and the frame 4 stable, synchronization springs 10located between the tilting plates 2 and the frame 4 are intended.

If the gyroscope now starts rotating about the x axis, Coriolis forcesoccur that make the tilting plates 2 arranged on the x axis to protrudefrom the x-y plane. Owing to the predetermined elasticity of the tiltingsprings 8 and the synchronization springs 10, the tilting plates 2 lyingon the x axis rotate about the y axis or about the tilting springs 8into and out of the drawing plane. For this purpose, the tilting springs8 have been executed in a way to allow, on the one hand, the drivingmovement of the tilting plates 2 about the z axis and, on the otherhand, to not substantially impede the tilting about the y axis. Aboutthe x axis, however, the tilting springs 8 are largely rigid on thetilting plates 2 located on the x axis. The same applies to a rotationalspeed of the gyroscope about they axis. In this case, the tilting plates2 located on they axis tilt out of the x-y plane and indicate thecorresponding Coriolis force acting upon the tilting plates 2. Thecorresponding tilting springs 8 of these tilting plates 2 are executedanalogously to the other tilting springs; owing to their arrangement anddesign, they allow a rotation of the tilting plates 2 positioned on they axis about the z axis and a tilting movement about the x axis. On theother hand, they have an essentially rigid design about the y axis. Thesynchronization springs 10 are designed in a way to also allow thetilting movement of the tilting plates 2 out of the x, y drawing plane.However, they pass on the tangential movement about the z axis to theneighboring structural part. Accordingly, they have been designedlargely rigid for the forces that act in tangential direction.

The z mass 3 and the frame 4, among other, serve as indicators of thegyroscope's z rotational speed. The primary movement completes itselftogether with the tilting plates 2 in tangential direction about the zaxis too. The drive takes place with comb electrodes 11 and 11′, inwhich case the comb electrodes 11 are arranged on the frame 4, whereasthe comb electrodes 11′ are stationary fastened on the substrate. Thetangential movement about the z axis is supported by the frame springs6, which allow the tangential movement, but largely impede a radialmovement of the frame 4 in this direction owing to their respectiverigidity.

Due to the tangential primary movement, Coriolis forces occur in radialdirection as soon as the gyroscope rotates about the z axis. The frame 4cannot yield in radial direction owing to the suspension on the framesprings 6 and the synchronization springs 10. The z mass 3, on the otherhand, has been suspended from the frame 4 with its springs 5 in such away that it can yield in radial direction of the Coriolis force. Thesprings 5 with which the z mass 3 is fastened to the frame 4 have beenset in such a way to each other that z mass 3 is made more insensitiveagainst parasitic rotational torques that occur solely from the primarytangential movement. As a result of this, the z mass 3 reactsessentially only to Coriolis forces that occur due to a rotational speedalong the z axis.

To determine the z rotational speed without interference, the z mass 3is connected to a sensor element 12. This sensor element 12 is fastenedto the tie bolt 9 and to two tie bolts 14 with sensor springs 13. Inaddition, the sensor element 12 is connected to the z mass 3 via acoupling spring 15. The coupling spring 15 is executed non-rigidly intangential direction and stiffer in radial direction. As a result ofthis, a decoupling between the drive movement of the z mass intangential direction and the sensor and secondary movement in radialdirection occurs. While the z mass is driven in tangential directionwithout this having a significant effect on the sensor element 12, whena Coriolis force occurs the z mass 3 is moved outwards and inwards, andwhile doing so it carries the sensor element 12 due to the correspondingspring stiffness of the coupling spring 15. With respect to their springstiffness, the sensor springs 13 are likewise executed in such a waythat they hardly impede the sensor element 12 in radial direction—inother words, that in this direction they have a relatively low (and inany case precisely adjustable) spring stiffness and at the same timethey largely impede the movements of the sensor element 12 in tangentialdirection. This decouples the primary movement from the secondarymovement, so that the sensor element 12 can indicate a Coriolis forceoccurring in radial direction only through a corresponding oscillatingmovement in radial direction. The mesh structure of the sensor element12 thus implements the movable electrode of a capacitor whose staticopposite pole is fixed on the substrate within the recesses and notdrawn. This variable capacity serves the purpose of converting theregistered movement into an electric signal.

For a better understanding, the following figures show the gyroscope'sindividual elements detached from the other structural elements.

FIG. 2 shows the tilting plates 2. Every tilting plate 2 is fastened totwo tie bolts 9 with the help of two tilting springs 8. The tiltingsprings 8 allow on the one hand the tangential oscillating primarymovement of the tilting plates 2 and, on the other hand, they also allowthe tilting of the tilting plates 2 out of the x-y plane around thetilting springs 8. In radial direction, on the other hand, the tiltingsprings 8 have been stiffly executed so that the tilting plates 2 arenot significantly deflected by a Coriolis force acting in radialdirection that indicates a z rotation of the gyroscope. Therefore, apredetermined deflection of the tilting plates 2 occurs due to arotational speed about the x or y axis.

According to FIG. 3, the tilting plates 2 of FIG. 2 are connected withthe frame 4 and synchronization springs 10. The unit shown here is setinto a synchronous tangential motion about the z axis as primarymovement. The connecting springs 10 synchronize the tangential movementof the tilting plates 2 and the frame 4. Speed differences among thecomponents, which could possibly occur owing to tolerances in theproduction of the gyroscope, are offset by the synchronization springs10. The individual structural parts thus oscillate with a commonresonance frequency and therefore indicate rotational speeds in the sameway.

FIG. 4 shows the structural parts that are essential for registering a zrotational speed. In the primary movement, the z mass 3 is set into anoscillating tangential motion about the z axis together with the frame 4(not shown here). Reacting to the gyroscope's rotation about the z axis,the z mass 3 is stimulated to a radial oscillation. The z mass 3 isconnected to the sensor element 12 via the coupling spring 15. Sensorsprings 13 fasten the sensor element 12 to the tie bolts 9 and 14. Thesensor springs 13 allow the sensor element 12 to make a radial movement,which during the course of registering a rotational speed about the zaxis is coupled by the radial oscillation of the z mass 3. The transferof the radial movement from the z mass 3 to the sensor element 12 ismade possible by the coupling spring 15, which is on the one handsufficiently non-rigid for not transferring the tangential primarymovement of the z mass 3 to the sensor element 12 and on the other handsufficiently rigid to make the secondary movement of the z mass 3 aradial movement of the sensor element 12. Four of the correspondingstructural parts have been arranged on the gyroscope's substrate at a90-degree angle to one another. Here, they are located between the x andy axis on the median line.

A detailed view of the structural elements for determining the zrotational speed is shown once again in FIG. 5. The z mass 3 is fastenedto the frame 4 with springs 5. The frame 4 is fastened to the frame tiebolt 7 via the frame springs 6 that are non-rigid in tangentialdirection. Apart from being fastened to the tie bolt 9, the sensorelement 12 is also arranged on the tie bolts 14. These tie bolts 14 can,in addition to their function as fixation points for springs 13, alsoserve as stoppers for the primary movement of the frame 4 and thetilting plates 2 too. The radial movement of the z mass 3 is transferredvia the coupling spring 15 to the sensor element 12, which is also setinto a radial oscillating motion together with the z mass 3 as soon as aCoriolis force indicates a z rotational speed.

FIG. 6 shows a schematic view of the gyroscope's primary movement. Itbecomes apparent that the tilting plates 2 and the frames 4 are set intoan oscillating rotation about the z axis with the z masses 3. In thiscase, the tie bolts 14 serve as stoppers of the tilting plates 2 and theframe 4. In this primary movement, the sensor elements 12 remainarranged on the substrate without moving. The drawing is schematic as inthe following figures, which is why the details can be a littleinaccurate.

FIG. 7 shows the deflection of the tilting plates 2 located on the xaxis, and this deflection indicates the gyroscope's x rotational speed.The tilting plates 2 located on the x axis are tilted out of the x-yplane around the tilting springs 8 with which they are fastened to thetie bolts 9. The tilting elements 2 located on they axis, on the otherhand, remain on this plane. Owing to the spring stiffness of thesynchronization springs 10, the frames 4 and the z masses 3 are alsotilted in this embodiment, but due to the softness of the couplingsprings 15, these deflections do not disrupt the sensor element 12.Thanks to plate capacitors (whose movable one-half is formed by thetilting plate 2 itself) and their static one-half located below theallocated tilting plate 2 on the substrate, the respective tiltingmovements can be converted to an electric signal. Due to the softness ofthe coupling springs 15, these movements have no effect on the sensorelements 12. Similarly, a y rotational speed can be registered. In thiscase, the tilting plates 2 (which are arranged along they axis) tilt outof the x-y plane. If applicable, as a result of this, the z masses 3 andthe frames 4 (which are fastened to the tilting plates 2 via thesynchronization springs 10) are also moved out of the x-y plane, atleast partially.

FIG. 8 shows a schematic view of how a gyroscope's z rotational speed isregistered. Here, the Coriolis force sets the z masses 3 intooscillating motions going in radial direction, as already describedabove. In this movement of the z mass 3, the coupling spring 15 causesthe sensor element 12 to move in radially oscillating fashion too. Thecorresponding springs are designed so the sensor element 12 can be movedslightly in radial direction, but stay rigid in a direction out of thex-y plane or in tangential direction about the z axis. The radialmovement of the sensor element 12 can be determined on its meshstructure with the corresponding electrodes that are fastened instationary fashion on the substrate. For registering the z rotationalspeed, both the tilting plates 2 and the frame 4 remain largely rigid.If need be, however, and depending on the respective spring constants,the frame 4 can be slightly deflected in radial direction.

This invention is not restricted to the embodiments shown. Inparticular, modifications such as the design of the individualstructural parts and their mutual arrangement are possible in a mannerdifferent from the one shown here, as far as they remain within theframework of the applicable patent claims.

REFERENCE LIST

1 Substrate

2 Tilting plate

3 zmass

4 Frame

5 Spring

6 Frame spring

7 Frame tie bolt

8 Tilting spring

9 Tie bolt

10 Synchronization spring

11 Comb electrode

11′ Counter electrode

12 Sensor element

13 Sensor spring

14 Tie bolt

15 Coupling spring.

What is claimed is:
 1. A gyroscope for detecting movement around a zaxis, the gyroscope comprising: a substrate; at least one anchor coupledto the substrate; a first driving mass coupled to the at least oneanchor, the first driving mass radially oscillate with respect to alocation on the substrate; a second driving mass coupled to the at leastone anchor, the second driving mass radially oscillate with respect to alocation on the substrate; a first sensor electrode coupled to the firstdriving mass, the first sensor electrode detects a first capacitivechange caused by a rotational movement around the z-axis and generates afirst signal; and a second sensor electrode coupled to the first drivingmass, the second sensor electrode detects a second capacitive changecaused by the rotational movement around the z-axis and generates asecond signal, the first and second signals relate to a differentialmeasurement of the rotational movement around the z-axis.
 2. Thegyroscope of claim 1 wherein the first sensor electrode comprises afirst plate electrode located above the first driving mass.
 3. Thegyroscope of claim 2 wherein the first plate electrode moves in responseto rotational motion about the z-axis, the first plate electrodemovement causes the first capacitive change within the first sensorelectrode.
 4. The gyroscope of claim 3 wherein the first plate electrodeand the first sensor electrode are in the same plane.
 5. The gyroscopeof claim 3 wherein the first plate electrode is on a side surface of thefirst driving mass and the first sensor electrode is located adjacent toand in the same plane as the first driving mass.
 6. The gyroscope ofclaim 1 wherein the second sensor electrode comprises first and secondplates, the first and second sensor electrodes move relative to eachother to detect in-plane capacitive movement between the first andsecond plates.
 7. The gyroscope of claim 1 wherein oscillation of thefirst and second driving masses are synchronized with each other usingat least one spring.
 8. The gyroscope of claim 7 wherein the first andsecond driving masses oscillate along a first axis and are 180 degreesout of phase from each other.
 9. The gyroscope of claim 7 wherein thefirst and second driving masses are separated by the central anchor andthat oscillate at 180 degrees out of phase from each other.
 10. A methodfor detecting rotational rate about a z-axis, the method comprising:causing radial oscillation of a first pair of driving masses relative toa location on a substrate, the first pair of driving masses oscillating180 degrees out of phase with each other and along a first axis;detecting a first capacitance change within a first sensor electrodeassociated with a first driving mass within the first pair of drivingmasses; detecting a second capacitance change within a second sensorelectrode associated with a second driving mass within the second pairof driving masses; and determining a first rotation rate about thez-axis based at least in part on the first and second capacitancechanges.
 11. The method of claim 10 wherein the first pair of drivingmasses are coupled using a plurality of springs.
 12. The method of claim10 wherein the first pair of driving masses are coupled using a firstjoint at the location on the substrate, the first joint allowing thefirst pair of driving masses to deflect and sense differentialmeasurements related to the first rotational rate.
 13. The method ofclaim 10 wherein the oscillation of the first pair of driving masses isat least partially controlled by a plurality of springs.
 14. The methodof claim 13 wherein the plurality of springs provides synchronizedoscillation of the first pair of driving masses.
 15. The method of claim10 wherein at least two driving electrodes drive the radial oscillationof the first pair of driving masses.
 16. A gyroscope comprising: asubstrate; an anchor coupled to the substrate; a first drive masscoupled to the anchor, the first drive mass radially oscillates along afirst axis; a second drive mass coupled to the anchor, the second drivemass radially oscillates along the first axis and is synchronized withthe first drive mass; and a first synchronization spring coupling thefirst and second drive masses, the synchronized radial oscillation ofthe first and second drive masses being at least partially controlled bythe first synchronization spring.
 17. The gyroscope of claim 16 furthercomprising: a first sensor coupled to the first drive mass, the firstsensor detects movement around a z-axis; a second sensor coupled to thesecond mass, the second sensor detects movement around the z-axis; andwherein the first and second sensors generate signals from which a firstdifferential measurement is derived.
 18. The gyroscope of claim 17further comprising: a first sensor electrode associated with the firstsensor, the first sensor electrode detects a first capacitive changecaused by a first movement around the z-axis; and a second sensorelectrode associated with the second sensor, the second sensor electrodedetects a second capacitive change caused by the first movement aroundthe z-axis.
 19. The gyroscope of claim 18 wherein the first sensorelectrode comprises a first plate electrode and a second plate electrodethat move tangentially to each other.
 20. The gyroscope of claim 16further comprising: a first drive element coupled to the first drivemass, the first drive element causing the first drive mass to radiallyoscillate along the first axis; and a second drive element couple to thesecond drive mass, the second drive element causing the second drivemass to radially oscillate.